package com.lord.util;

import java.security.MessageDigest;
import java.util.Arrays;

/**
 * @Description: 验证消息的确来自微信服务器
 * @author Lord
 * @date 2017-3-20 下午3:55:18
 */
public class CheckUtil {
	
	private static final String token = "lord";
	
	public static boolean checkSignature(String signature, String timestamp, String nonce){
		String[] arr = new String[]{token,timestamp,nonce};
		//排序
		Arrays.sort(arr);
		
		//生成字符串
		StringBuffer content = new StringBuffer();
		for (int i = 0; i < arr.length; i++) {
			content.append(arr[i]);
		}
		
		//sha1加密
		String temp = getSha1(content.toString());
		
		return temp.equals(signature);
	}
	
	
	/**
	 * @Title: getSha1
	 * @Description: sha1加密
	 * @param str 需要加密的字符串
	 * @return 加密后的字符串
	 * @author Lord
	 * @date 2017-3-20 下午4:09:06
	 */
	public static String getSha1(String str){
        if(str==null||str.length()==0){
            return null;
        }
        char hexDigits[] = {'0','1','2','3','4','5','6','7','8','9',
                'a','b','c','d','e','f'};
        try {
            MessageDigest mdTemp = MessageDigest.getInstance("SHA1");
            mdTemp.update(str.getBytes("UTF-8"));

            byte[] md = mdTemp.digest();
            int j = md.length;
            char buf[] = new char[j*2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                buf[k++] = hexDigits[byte0 >>> 4 & 0xf];
                buf[k++] = hexDigits[byte0 & 0xf];      
            }
            return new String(buf);
        } catch (Exception e) {
            return null;
        }
    }
	
}
